IoSiS: a radar system for imaging of satellites in space

Space debris nowadays is one of the main threats for satellite systems especially in low earth orbit (LEO). More than 700,000 debris objects having potential to destroy or damage a satellite are estimated. The effects of an impact often are not identifiable directly from ground. Hence highresolution radar images are an appropriate tool for analyzing satellite structures. Therefor DLR is currently developing a radar system called IoSiS (Imaging of Satellites in Space), being presently based on an existing steering antenna facility and our multi-purpose high-performance radar system GigaRad [3], developed and constructed for multi-purpose experimental investigations. GigaRad is a multi-channel system operating at X band and using a bandwidth of up to 4.4 GHz in the IoSiS onfiguration, providing fully separated transmit (TX) and receive (RX) channels, and separated antennas. For the observation of small satellites or space debris a high-power traveling-wave-tube amplifier (TWTA) is mounted close to the TX antenna feed. For the experimental phase IoSiS uses a 9 m TX and a 1 m RX antenna mounted on a common steerable positioner. High-resolution radar images are obtained by using Inverse Synthetic Aperture Radar (ISAR) techniques. The guided tracking of known objects during overpass allows wide azimuth observation angles. Thus high azimuth resolution comparable to the range resolution can be achieved. This paper outlines technical main characteristics of the IoSiS radar system including the basic setup of the antenna, the radar instrument and the corresponding RF error correction methodology, and the measurement strategy. Also a short description about a simulation tool for characterizing the whole instrument and exploring the expected nature of the radar images are discussed